package com.xyzq.cgate.common.utils;

import com.xyzq.cgate.common.exception.CgateException;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @Description:
 * @author chenchen
 * @date 2019/6/24 9:37
 */
public class HashUtil {

    public static long hash(final String key) {
        // md5 byte
        MessageDigest md5;
        try {
            md5 = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new CgateException("MD5 not supported", e);
        }
        md5.reset();
        byte[] keyBytes;
        try {
            keyBytes = key.getBytes("UTF-8");
        } catch (UnsupportedEncodingException e) {
            throw new CgateException("Unknown string :" + key, e);
        }

        md5.update(keyBytes);
        byte[] digest = md5.digest();

        // hash code, Truncate to 32-bits
        long hashCode = (long) (digest[3] & 0xFF) << 24
                | ((long) (digest[2] & 0xFF) << 16)
                | ((long) (digest[1] & 0xFF) << 8)
                | (digest[0] & 0xFF);
        return hashCode & 0xffffffffL;
    }
}
